Why can uv light hurt people？What to do if injured by UV light？

Ultraviolet rays are electromagnetic waves with a wavelength of 100-400nm. According to different wavelengths and biological effects, it is mainly divided into three bands, long-wave ultraviolet UVA, medium-wave ultraviolet UVB and short-wave ultraviolet UVC. Ultraviolet rays account for about 13% of sunlight. In nature, UVA accounts for about 97% and UVB accounts for only 3%. The ultraviolet rays used for sterilization are mainly short-wave ultraviolet rays UVC. Generally speaking, the shorter the wavelength of ultraviolet light, the stronger the lethality.

In most hospitals, indoor air disinfection is carried out by using ultraviolet disinfection lamps and ultraviolet disinfectors. This method is simple and easy to implement. The wavelength range from the inner surface of the ultraviolet lamp is 200-280nm, and the central wavelength of sterilization is 275nm, which belongs to short-wave ultraviolet. This type of ultraviolet radiation mainly kills microorganisms by damaging microorganisms (bacteria, viruses, spores and other pathogens) and destroying nucleic acids, thereby achieving the purpose of disinfection.

Long-term exposure to ultraviolet light can cause skin pigmentation, thickening and rough skin, photoaging, and serious precancerous lesions, skin cancer, cataracts, etc. Therefore, long-term ultraviolet exposure should be avoided. However, the main hazards caused by short-term exposure to ultraviolet disinfection lamps are electro-optic ophthalmia and skin damage, and other carcinogenic risks are minimal. "The sterilized ultraviolet lamp is a short-wave UVC with very weak penetrating power, which is mainly harmful to the skin surface. How much damage the ultraviolet disinfection lamp causes to the human body depends on the power and the irradiation time."

After some people have been exposed to ultraviolet disinfection lamps, the skin peels like "Vitiligo". Some experts say that the damage caused by ultraviolet rays to the skin is related to the tolerance of the individual's skin. Irradiation for one hour can cause symptoms similar to solar dermatitis. The skin becomes red, dark, and dry. The patient will have pain, molting, and even blisters in severe cases. This is an allergic reaction of the skin to ultraviolet rays. Patients can go to the dermatology department for anti-allergic and skin care treatments. Normal "sunburn" will heal in about 1-2 weeks. According to clinical experience, there are no skin ulcers, breakages, infections, etc., and no scars are left. Pigmentation will gradually improve as the skin recovers. During the recovery period, patients should take care to avoid sun exposure, reduce the time spent on computer, TV, mobile phone and other screens, keep their diet light, and generally mildly burned skin and hair, such as skin and hair, can heal quickly without sequelae.

A recent Columbia University study showed that continuous 222nm far ultraviolet (UVC) light can kill influenza viruses in the air without harming human tissues. In other words, the use of far-ultraviolet lamps in public places such as hospitals, doctors’ offices, schools, airports, airplanes, etc., can make a powerful check on seasonal influenza epidemics and pandemics.